Metal cutting tool



W. E. DOW

METAL CUTTING TOOL Filed Feb, 1, 1956 ocx. s, 1959 I Ill ifm/'se 47%@ ww@ mow, WN

9 99 W i n 1.5mm@ x Unite METAL cUrrING rooL Application February 1, '1956, Serial No. 562,820

3 Claims. (Cl. 29-98) This invention relates to metal-cutting tools and-more particularly to a new and improved cutoi tool and holder therefor.

In many production operations a cuto tool is ernployed at one station of a multi-station automatic machine. Inasmuch as a cutoif tool will normally dull much faster than other tools in the machine, it is frequently the case that an entire machine must be shut down more frequently than is desired in order to replace a dulled cutoff tool. To replace the tool, it is usually necessary to remove the tool and toolholder and replace it, which often then necessitates a re-setup of the affected station of the machine. Obviously, such a process is time-consumin-g and costly.

It is a particular aim of this invention to provide a cutoff tool of novel and improved operating principle and construction whereby the performance of the cutting tool is superior to that obtainable with existing cutoff tools and whereby the frequency that the tool and holder must be removed from the machine for regrinding of the tool is substantially reduced.

It is another object of this invention to provide a cutv'off tool and holder assembly which provides a novel and improved means of tool support and which is simple and economical to manufacture.

Other objects will be in part obvious, and in part pointed out more in detail hereinafter.

The invention accordingly consists in the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereafter set forth and the scope of the application of which will be indicated in the appended claims.

In the drawings:

Fig. 1 is a fragmentary side view of a cutoi tool and holder assembly constructed in accordance with this invention,

Fig. 2 is a fragmentary top view of the cutoff tool and holder assembly of Fig. 1,

Fig. 3 is a fragmentary top view of a portion of the assembly of Fig. 1,

Fig. 4 is an end view of the cutter and holder assembly of Fig. l,

Fig. 5 is a fragmentary sectional view along the line 5-5 of Fig. l, and

Fig. 6 is a perspective view of a cutoff tool of modified construction.

With reference to the drawings, an embodiment of a cutoff tool and holdei assembly constructed in accordance with this invention is comprised of a rigid holder 10 of generally rectilinear construction having a blade support portion 11 extending axially from one end thereof, the blade support portion 11 is of a lesser thickness than the remainder of the holder 10 thus forming a shoulder 13 extending transversely of one side ofthe holder. The blade support 11 is provided with an inclined peripheral edge 12 which, as will be later apparent, serves to provide clearance for a workpiece associated with the tool. A bushing 14 extends through 4attent 2,907,099 lPatented Oct. 6, 1959 `the bushing relative to the holder.

A cutoff blade 20 which will be described in detail hereinafter is mounted on the bushing 14 with a side 21 of the blade engaging with the toolsupport 11. A clamping plate 22 is also mounted on the bushing 14 and is provided with a recess 23 forming spaced apart parallel bearing surfaces or shoulders 24 and 25 engaged with the side 26 of the blade Ztl. The clamping plate 22 is provided with a peripheral edge portion 28 engageable with the shoulder 13 of the holder to maintain an edge portion 27 thereof in alignment with the inclined edge 12 of the holder. A threaded member such as the socket head cap screw 29 is received in the threaded bore of the bushing and a washer 3i) is provided between the head of the screw and the clamping plate 22. By threading the screw 29 inwardly of the bushing, the blade 2.0 may be securely clamped between the plate 22 and the blade support 11 to prevent the blade from being displaced longitudinally of its pivotal axis and relative to the holder.

As can be seen from the drawings, the cut-off blade l20 is of novel construction whereby the blade is comprised of a hub portion 34 having three radially extending'cutting arms 35, 36, 37, spaced equiangularly about an axial aperture 38 in the hub portion. The arms of the blade 20 are provided with tip portions 35a, 36o., and 37a, respectively, which'are preferably of a material such as carbide. In accordance with the invention the face 39 of each of the blade tips is disposed in an arc of a circle disposed coaxially with the pivotal axis of the blade and is provided with the usual side clearance as at 40 and end clearance as'at 41. To prevent canting of the blade within the holder and to provide the rmest support for the blade, the blade engaging face of the blade support 11 is relieved as at 50 and 51 which in cooperation with the recess 23 provided in the clamping plate 22 compensates for the side clearance of the blade bits and permits the clamping of the blade Within the holder along the flat portions of the blade.

With particular reference to Fig. l, it can be seen tha when the blade is used with a workpiece as represented at 42, with the workpiece turning in the direction of the arrow, the radius of the cutting edge 43 of the arm 35 is parallel to the radius of the workpiece 42 which is normal to the radius of the point of contact of the workpiece with the blade. While the reasons therefor are not completely understood, it has been found that a cutoff tool constructed and set up in the manner described provides a much better chip and a far superior cutting action than that provided by conventional circular or straight cutoff blades. Further, it has been found that the carbide tips of a cutoff blade constructed in accordance with this invention tend to resist breakage and thus have a service life much greater than conventional carbide tipped cutoif blades. The work-engaging arm which, in the ydrawings is the arm 3S, is supported in the desired relationship to the workpiece by means of a backup rod 46 slidably mounted in the holder 1l) and extending longitudinally thereof with one end 47 of the rod extending beyond the shoulder 13 of the holder and engaging the edge of the arm 35 which faces the shoulder 13. The backup rod 46 is positioned by means such as setscrew 49 threadably received in the holder in longitudinal alignment with the rod and engaging the other end of the rod. rlhe backup rod 46 provides a simple, inexpensive means of support for the blade to prevent rotation thereof during use. Further, the use of the setscrew 49 to position the backup rod and support it against longitudinal displacement during the cutting operation provides a means for accurately adjusting the cutting edge of the tool relative 'to the workpiece, In many cases after a tool holder has been set up on a machine a slight adjustment of perhaps a few thousandths of Lau inch is desirable to obtain optimum cutting performance and with the tool holder constructed in accordance with the invention it is possible to obtain this line adjustment by means of the setscrevv 49 Without necessitating any adjustment of the holder itself.

As should be apparent from the drawings and the above description, one of the particular advantages of a cutoff tool and holder assembly constructed in accordance with the invention is that the blade 20 may be used with `the tip of the arm 3S in cutting engagement with the work until such time as its tip 35a becomes dulled, whereupon one of the other tips 36a or 37a may be rotated into cutting engagement with the work without the necessity of removing the tool holder from the machine and, in fact, Without lthe necessity of removing the blade from the holder.

When it is desired to present a new cutting edge, it is only necessary to back out the screw 29 and draw the clamping plate 22 and tool 20 outwardly of the holder and out of interference with the backup rod 46 and then rotate a new cutting edge into work-engaging position. {Inasmuch as the backup rod will not have been disturbed relative to its longitudinal disposition, the new cutting edge will be automatically set up in the proper workengaging relation when the arm carrying the new cutting edge is engaged with the backup rod and the blade clamped between the tool support 11 and the clamping plate 22. During proper use of the tool, as illustrated in Fig. 1, 'the cutting edge is directly above the pivotal axis of the blade and thus the force exerted on the blade during cut- Vting will not impose any particular turning movement thereon as is in the case of circular forming tools wherein the cutting edge is located at a substantial radius from the pivotal axis of the blade, thus, obviously providing a much firmer support of the blade.

While the holder for the cutoff tool has been described in combination with a blade having three radially extending arms, the holder is equally as suitable for use with a blade wherein only two radial arms are provided inasmuch as in certain applications it may be preferable to use a two-armed blade. Fig. 6 illustrates such a modification of the cutoff tool which differs in construction from the blade 20 only to the extent that two, rather than three arms, are provided thereon.

Thus, it can be seen that there has been provided a cutoff blade and holder therefor of novel construction whereby within the limits of the number of arms provided on the blade, the cutoff blade need not be removed from the holder nor the holder removed from the machine in order to change the cutting edge thus very substantially reducing the down time of the machine caused by the replacement of dull cutoff blades. Further, the novel construction of the tool itself provides a longer service life between changes of cutting edges as well as prolonging the over-all life of the blade through the minimizing of tip breakage. The retention of the blade within the holder provides a much improved support of the blade against rotational and longitudinal displacement relative to the pivotal axis thereof and relative to the holder. Also, there has been provided a means of fine adjustment of the cutting edge of the blade relative the workpiece While the blade is on the machine in order to position the cutting edge for optimum performance of the blade without movement of the tool holder. The entire assembly is simple and economical to manufacture and yet is rugged and capable of use on machines and in operations wherein onlyvsmall tolerances are `allowed.

As many changes could be made in the above construc tion and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the language used in the following claims is intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

I claim:

1. In a cutoff -tool and holder' assembly for use with automatic lathes and the like, an elongated rigid tool holder having a shoulder disposed transversely thereof adjacent and facing one end thereof, a cylindrical bushing having a threaded-through bore mounted in the holder intermediate said shoulder and said one end of the holder with the longitudinal axis thereof disposed laterally of said shoulder, a clamping plate mounted on the bushing and having a at peripheral edge portion engaged with said shoulder, a metal cutting tool rotatably mounted on the bushing intermediate the holder and the clamping plate, said tool having a plurality of radially extending arms each provided with a cutting portion on the outer end thereof, the face of each of the cutting portions being disposed in an arc of a circle disposed coaxially of the pivotal axis of the tool, one of said arms extending gen erally parallel to said shoulder and having an edge portion facing said shoulder, screw means received inthe bore of said bushing and engaged with the clamping plate to clamp the tool between said clamping plate and the holder, an elongated back-up rod slidably mountedmin the holder and disposed longitudinally thereof, one end of the rod extending beyond said shoulder for engagement with said edge portion of said one arm adjacent the outer end thereof, and a setscrew threadably received in the holder in longitudinal alignment with said back-up rod and in engagement with the other end of said rod. i

2. In a cutoff tool for lathes and the like of the type having a work spindle wherein the tool is mounted for movement to and from the axis of the work spindle to engage a workpiece rotatably driven about said axis, said tool comprising a rigid holder, a cuto blade having a flat body portion, means mounting said fiat body portion on the holder for rotation about an axis normal to said at body portion, said cutoff blade having a plurality of cutting arms extending radially of the flat body portion, each of said arms having a cutting edge at the outer end thereof extending parallel to said axis of rotation of said -at body portion, means to clamp the cutoff blade in a rotated position on the holder wherein one of said arms is in a work engaging position and the cutting edge on that arm is in substantial vertical alignment with the axis of rotation of the flat body portion, and adjustable supporting means on said holder engaged with said cutoff blade and preventing movement of the cutting edge of said one arm about said axis of rotation during a cutting operatlon.

3. In a cutoii:` tool for lathes and the like of the type having a work spindle wherein the tool is mounted for movement to and from the axis of the work spindle to engage work rotatably driven about said axis, said tool comprising a rigid holder having a shoulder extending transversely thereof adjacent and facing one end thereof, a clamp plate having a flat peripheral edge portion, means mounting said clamp plate on said shoulder with said fiat peripheral edge portion in engagement lwith said shoulder to align the plate in a predetermined position rela tive to the shoulder, a cutoff blade clamped intermediate said shoulder and plate and rotatable relative thereto about an axis, said cutoff blade having a plurality of angularly spaced-apart arms, each of said arms having a cutting `edge on the outer end thereof disposed parallel to the axis of Irotation of said cutoff blade, said cutoff blade References Cited in the file of this patent being clamped between said clamp plate and said holder UNITED STATES PATENTS in a position wherein one of said arms is disposed in Work engaging position with the cutting edge on that arm ggg( sseett 15 in substantial Vertical alignment with the axis of rotation 5 1 260172l Mar" 19 1918 of said cutoff blade, and backup means constraining said 7402604 Kienz Dec` 4, 1929 one arm from moving about said axis of rotation during a cutting Operation FOREIGN PATENTS 138,369 Great Britain Feb. 12, 12o 

